Field of Invention
The present invention relates to a control field, and more particularly to a bath safety control system and a bath safety control method.
Description of Prior Art
Usually, two relays are electrically coupled between a high-voltage/high-current load and a power source. One of the two relays is a safety relay, and the other is an operation relay. The power source provides power for the load only when both the safety relay and the operation relay are turned on.
When the power source is supplied by electricity, the safety relay is turned on immediately and the operation relay remains turned off. When the load is operated, the operation relay is switched between turned-on and turned-off conditions according to a user's control. When the load stops operating, the safety relay remains turned on to decrease the number of switchings (the number of operations) of the safety relay as long as the power source is supplied by the electricity. When the power source is not supplied by the electricity, both the safety relay and the operation relay are turned off. When the operation relay has a fault, it is necessary to turn off the safety relay to prevent the load from being damaged.
For example, when the operation relay which is electrically coupled to a heater (or a pump) has a fault of sticking contacts, a water temperature is increased after the heater (or the pump) is operated for a long time. When the water temperature is increased to a dangerous temperature, a controller which utilized for controlling the safety relay and the operation relay controls the safety relay and the operation relay which are electrically coupled to the heater (or the pump) to be turned off.
In the above-mentioned safety mechanism of the load, it can be ensured that the safety relay can be successfully turned off every time to stop providing the power for the load because of the minimum number of switchings of the safety relay, especially when the operation relay has the fault of sticking contacts.
However, a situation that the safety relay is not successfully and immediately turned off to stop providing the power for the load may be occur when the operation relay has the fault of sticking contacts. Meanwhile, the load or a system including the load may be damaged.
Consequently, there is a need to provide a safety mechanism to solve the problem that the safety relay is not successfully and immediately turned off to stop providing the power for the load when the operation relay has the fault of sticking contacts in the prior art.